Carbamazepine is listed in Pregnancy Category D. A warning appears in the package insert.

Patients who require carbamazepine monotherapy to control their seizures can be advised that up to 90% of women who use it during pregnancy have normal, healthy babies. Approximately 0.5% of fetuses exposed to carbamazepine during weeks 4-6 have spina bifida, so Level II ultrasound at 16 weeks gestation is recommended, as is amniocentesis in selected cases. Minor craniofacial defects, fingernail hypoplasia, and developmental delay may occur somewhat more frequently.

The risk of defects is higher for women who take several medicines, and for women with a family history of birth defects.

Women who are capable of becoming pregnant should be advised to take 400 mcg (0.4 mg) of folic acid (folate) daily to help prevent neural tube defects. Women at high risk, such as those with a history of a neural tube defect in a previous pregnancy, should take 4000 mcg (4 mg) daily, beginning before they become pregnant.

Check the levels of carbamazepine in the woman's blood at intervals during pregnancy, since changes in her body may affect them. Dosage adjustments may be needed to prevent seizures or side effects.

During the last month of pregnancy, the woman should take 10 mg per day of vitamin K to prevent a bleeding disorder that affects some babies born to mothers who are taking anticonvulsants.

No studies have been performed to demonstrate the effect of specific AEDs during labor and delivery. Possible causes of seizures include:

• failure or inability to take medication
• sleep deprivation
• hyperventilation
• stress
• pain

If the mother is taking carbamazepine, a breast-fed newborn will get about 2-5 mg per day in the breast milk. The effect of such a dose has not been evaluated but is unlikely to be harmful for a healthy, full-term baby.